Cooling of photo-copying machines



Oct. 30, 1956 E. WOODHAM 2,768,555

COOLING OF PHOTO-COPYING MACHINES Filed July 23, 1954 2 Sheets-Sheet l Ifan 0gp Waco/MM y /itiomey E. WOODHAM COOLING OF PHOTO-COPYING MACHINESOct. 30, 1956 2 Sheets-Sheet 2 Filed July 25, 1954 Attorney UnitedStates Patent COOLING OF PHOTO-COPYING MACHINES Edward Woodham,Colchester, England, assignor to E. N. Mason & Sons Limited, Colchester,England, a British company Application July 23, 1954, Serial No. 445,428

Claims priority, application Great Britain August 5, 1953 3 Claims. (Cl.95-73) This invention relates to photo-copying machines of the typewherein a tubular light source or sources is or are located inside astationary or rotating transparent cylinder or part of a cylinder aroundwhich a drawing or other original to be copied and sensitised paper orother material, is moved. As lamps of considerable power are used, alarge amount of heat is generated, a considerable proportion thereofbeing in the infra-red region of the spectrum, thus causing thetransparent cylinder to become excessively hot, to the detriment of thedrawing or other original and the sensitised material.

As is well known, various systems of ventilation are employed, some ofthese systems drawing air from the centre of the cylinder by means ofmetal ducting and thus causing cooler air to flow in at both ends of thecylinder. Air can also be blown in at one end of the cylinder andallowed to pass out at the other end of the cylinder. Air may also bedrawn out at each end whilst cooler air is allowed to flow in to thecentre through ducting. It is also known to surround the tubular lightsource by a glass tube capable of transmitting ultra violet lightnecessary for exposing most types of photo-printing materials. Althoughthe glass tube has been fitted to prevent the transmission of theshorter wave length ultra violet light, which causes the formation ofozone in the surrounding atmosphere, it has also been found beneficialas it absorbs some of the heat given out by the light source and thusprevents the cylinder from becoming too hot.

According to the present invention a photo-copying machine of the typereferred to is provided with a transparent jacket of glass or othertransparent material, the material sold under the registered trademarkPyrex, or other heat resisting glass, the jacket being provided with twospaced sets of continuous slots or series of holes or spaced slots alonga portion or the entire length thereof, the jacket being located betweenthe tubular light source and the cylinder.

The invention will now be described by way of example with reference tothe accompanying drawings, wherein:

Fig. 1 is a cross-sectional view on the line II of Fig. 2 on an enlargedscale.

Fig. 2 is a perspective view of a portion of a photocopying machine.

Fig. 3 is a cross sectional view taken on the line II of Fig. 1.

Referring first to Figs. 1 and 2, a transparent jacket of heat resistingglass, consists of two semi-cylindrical parts 2, 2', axially spacedapart by two substantially oppositely located strips 4, provided withslots or holes 14, 14'. These slots or holes, 14, 14' are notnecessarily parallel and are preferably wider at the middle portion ofthe cylinder. The jacket 2, 2' is located between a light source locatedin a tube 3 and a stationary or rotary transparent cylinder 1 aroundwhich latter the drawing or the like to be copied and sensitisedmaterial is placed or moved. The ventilating system is so arranged inthe cylinder 1 that air is drawn out from each end of the jacket 2, 2 inthe di- 'ice rection of the arrows 16, 16' by suction. Cool air thusflows in through the slots or holes 14, 14 after flowing into theopposite ends of the main cylinder as indicated by the arrows 17, 17'.

The ventilating system may also be arranged so that the cool air isforced into the ends of the jacket 2, 2' and flows out through the holesor slots 14 and out between the jacket 2 or 2' and outer cylinder 1. Thepurpose of using a jacket of the material described is that it transmitsa large proportion of the longer wavelength ultraviolet light rayswhilst absorbing a large proportion of infra-red light rays.

By the arrangement according to the invention a transparent ventilatingduct is provided which has a selective transparency, whilst allowingbeneficial ultraviolet light to reach the sensitised material and at thesame time shielding the outer cylinder 1 and the materials around thecylinder 1 from the harmful heating effects of infrared radiations. Thelight source 3 may in addition be surrounded in the known manner by aglass tube for shielding the light source from direct currents of airfrom the slots or holes 14 in the jacket. The two halves of the jacket,when formed by two semi-cylindrical parts 2, 2', may be off-set slightlyby strips 4 and 4' in relation to each other, as shown in Figs. 1 and 3,so as to cause the air to enter the interior of the jacket tangentiallythus providing further means for shielding the light source from adirect current of cooler air.

As shown in Fig. 3 three light sources 12, 12', 12" may be provided.

Amongst the advantages of the present invention may be mentioned:

1. Delicate original drawings and sensitised material or the like areprotected from excessive heat during photocopying.

2. The light source may be operated at its correct temperature, thusgiving a higher efficiency.

3. Materials with better optical but poorer heat resisting propertiesthan glass, may be employed for the construction of the outer cylinder.

I claim:

1. In a photo-copying machine having a cylinder and a tubular lightsource located centrally and longitudinally within the cylinder, thecombination comprising, a jacket including a pair of transparentsubstantially semicylindrical elements located around said light source,means at each side of the elements for connecting and axially displacingthe same so that one element is offset laterally from the other, saidmeans having openings for causing air to travel tangentially relative tothe inner wall of each element, and forced air means at the ends of saidelements for moving air therethrough and between the outer surfaces ofsaid elements and the inner wall of the cylinder.

2. In a photo-copying machine having a cylinder and a tubular lightsource located centrally and longitudinally within said cylinder, thecombination comprising a jacket including a pair of transparentsubstantially semi-cylindrical elements located around said lightsource, the adja cent ends of said elements being relatively displacedaxially, and strips having medial air openings, said strip arrangeddiametrically relatively to and connecting said substantiallysemi-cylindrical elements in axially offset relation.

3. In a photo-copying machine according to claim 1, the provision of airchambers at opposite ends of said semi-cylindrical elements.

Szasz Nov. 26, 1940 Streich Apr. 12, 1949

